Editor's Note: This story first aired in December 2012. Since then, questions have been raised about the truthfulness of some of the account that Shin Dong-hyuk gave about growing up in a North Korean prison camp.

In January 2015, Blaine Harden, who had written a book about Shin's experiences, said that Shin had changed key parts of his story, including the timing and circumstances of his time in prison, his torture, and his eventual escape. Harden first disclosed these discrepancies to The Washington Post and also sent a statement to 60 Minutes.

We have not yet been able to reach Shin for comment.

The following is a script from "Three Generations of Punishment" which aired on Dec. 2, 2012. Anderson Cooper is the correspondent. Andy Court, producer.

Tonight we're going to tell you about a place so brutal and horrific it's hard to believe it exists. It is, by all accounts, a modern-day concentration camp, a secret prison hidden in the mountains, 50 miles from North Korea's capital, Pyongyang. It's called Camp 14, and according to human right rights groups, it's part of the largest network of political prisons in the world today. Some 150,000 people are believed to be doing hard labor on the brink of starvation in these hidden gulags. But it's not just those who have been accused of political crimes; it's their entire families -- grandparents, parents, and children. A practice called "three generations of punishment."

Very little was known about Camp 14 until a young man showed up in South Korea with an extraordinary tale to tell. His name is Shin Dong-hyuk and he said he had not only escaped from Camp 14, but he was born there. He's believed to be the only person born and raised in the camps who's ever escaped and lived to tell about it.

Anderson Cooper: Did anybody ever explain to you why you were in a camp?

Shin Dong-hyuk: No. Never. Because I was born there I just thought that those people who carry guns were born to carry guns. And prisoners like me were born as prisoners.

Anderson Cooper: Did you know America existed?

Shin Dong-hyuk: Not at all.

Anderson Cooper: Did you know that the world was round?

Shin Dong-hyuk: I had no idea if it was round or square.

Camp 14 was all that Shin Dong-hyuk: says he knew for the first 23 years of his life. These satellite images are the only glimpse outsiders have ever gotten of the place. Fifteen thousand people are believed to be imprisoned here -- forced to live and work in this bleak collection of houses, factories, fields, and mines, surrounded by an electrified fence.

Anderson Cooper: Growing up, did you ever think about escaping?

Shin Dong-hyuk: That never crossed my mind.

Anderson Cooper: It never crossed your mind?

Shin Dong-hyuk: No. Never. What I thought was that the society outside the camp would be similar to that inside the camp.

Anderson Cooper: You thought everybody lived in a prison camp like this?

Shin Dong-hyuk: Yes.

Shin told us that this is the house where he was born. His mother and father were prisoners whose marriage, if you could call it that, was arranged by the guards as a reward for hard work.

Anderson Cooper: Did they live together? Did they see each other every day?

Shin Dong-hyuk: No. You can't live together. My mother and my father were separated and only when they worked hard could they be together.

Anderson Cooper: Did they love each other?

Shin Dong-hyuk: I don't know. In my eyes we were not a family. We were just prisoners.

Anderson Cooper: How do you mean?

Shin Dong-hyuk: You wear what you're given, you eat what you're given, and you only do what you're told to do. So there is nothing that the parents can do for you and there's nothing that the children can do for their parents.

Anderson Cooper: This may be a very dumb question, but did you even know what love was for the first 23 years of your life?

Shin Dong-hyuk: I still don't know what that means.

Love may have been absent, but fear was not. In this building, a school of sorts, Shin says he watched his teacher beat a little girl to death for hoarding a few kernels of corn -- a violation of prison rules, which he and the other students were required to learn by heart.

Shin Dong-hyuk: If you escape, you would be shot. If you try to escape or plan to escape, you would be shot. Even if you did not report someone who is trying to escape, you would be shot.

The shootings took place in this field, he says. The other prisoners were required to watch. As frightening as the executions were, Shin considered them a break from the monotony of hard labor and constant hunger. The prisoners were fed the same thin gruel of cornmeal and cabbage day-in and day-out. They were so hungry, Shin says, they ate rats and insects to survive.

Anderson Cooper: So for 23 years you were always hungry?

Shin Dong-hyuk: Yes. Of course. We were always hungry. And the guards always told us, "Through hunger you will repent."

What Shin and his family were repenting for probably dates back to the Korean War, when two of his uncles reportedly defected to the South. Shin believes that's why his father and grandfather were sent to Camp 14 and why he was supposed to live there until he died. North Korea's first dictator Kim Il Sung instituted this practice of "three generations of punishment" back in the 1950s.

David Hawk: The idea is to eliminate this lineage-- to eliminate the family-- on the theory that if the grandfather was a counterrevolutionary, the father and the grandsons would be opposed to the regime, as well.

David Hawk is a human rights investigator who's interviewed dozens of former prisoners and guards from the six political prison camps operating in North Korea today.

David Hawk: The largest number of people in the prison camps are those who are the children or grandchildren of people considered to be wrongdoers or wrong thinkers.

Anderson Cooper: I've never heard of anything like that.

David Hawk: It's unique in the 20th or 21st century. Mao didn't do it, Stalin didn't do it-- Hitler, of course, tried to exterminate entire families. But in the post-World War II world, it's only Korea that had this practice.

North Korea denies it has any political prisons, but refuses to allow outside observers to inspect Camp 14 and other sites.

Anderson Cooper: There's no way to verify all the details of Shin's story. Do you believe his story?

David Hawk: Oh, sure. His story is consistent with the testimony of other prisoners in every respect.

There's also physical evidence he carries around with him to this day. The tip of his finger is missing. He says it was chopped off as punishment when he accidentally broke a machine in a prison factory. He also has serious scars on his back, stomach, and ankles, which he was willing to show us, but embarrassed to show on camera. He says he received those wounds here, in an underground torture center. He was tortured because his mother and older brother were accused of trying to escape. He was just 13 years old at the time.

Anderson Cooper: Did they think that you were involved in the escape?

Shin Dong-hyuk: I'm sure they did.

Anderson Cooper: How did they torture you?

Shin Dong-hyuk: They hung me by the ankles. And they tortured me with fire. And from the scars that I have, the wounds on my body, I think they couldn't have done any more to me.

Shin says he tried to convince his interrogators he wasn't part of the escape plot. He didn't know if they believed him until one day when they took him to that field used for executions. Thousands of prisoners were already there waiting.

Shin Dong-hyuk: When I went to the public execution site I thought that I might be killed. I was brought to the very front. But that's where I saw my mother and my brother being dragged out and that's when I knew that it wasn't me.

Anderson Cooper: How did they kill your mother?

Shin Dong-hyuk: They hung her and they shot my brother.

He speaks of it still without visible emotion, and admits he felt no sadness watching his mother and brother die. He thought they got what they deserved. They had, after all, broken the prison rules.

Blaine Harden: He believed the rules of the camp like gospel.

Blaine Harden is a veteran foreign correspondent who first reported Shin's story in The Washington Post and later wrote a book ["Escape from Camp 14," by Blaine Harden] about his life.

Anderson Cooper: He had no compass by which to judge his behavior.

Blaine Harden: He had a compass. But the compass were the rules of the camp, the only compass he had. And it was only when he was 23, when he met somebody from the outside, that that started to change.

Anderson Cooper: When he met Park.

Blaine Harden: When he met Park.

Park was a new prisoner Shin says he met while working in Camp 14's textile factory. Unlike Shin, Park had seen the outside world. He'd lived in Pyongyang and traveled in China, and he began to tell Shin what life was like on the other side of the fence.

Shin Dong-hyuk: I paid most attention to what kind of food he ate outside the camp.

Anderson Cooper: What kind of food he had eaten?

Shin Dong-hyuk: A lot of different things. Broiled chicken. Barbecued pig. The most important thing was the thought that even a prisoner like me could eat chicken and pork if I were able to escape the barbed wires.

Anderson Cooper: I've heard people define freedom in many ways. I've never heard someone define it as broiled chicken.

Shin Dong-hyuk: I still think of freedom in that way.

Anderson Cooper: That's what freedom means to you?

Shin Dong-hyuk: People can eat what they want. It could be the greatest gift from God.

Anderson Cooper: You were ready to die-- just to get a good meal?

Shin Dong-hyuk: Yes.

He got his chance in January 2005, when he says he and Park were gathering firewood in this remote area near the electrified fence. As the sun began to set, they decided to make a run for it.

Blaine Harden: And as they ran towards the fence, Shin slipped in the snow. It was a snowy ridge, fell on his face. Park got to the fence first and thrust his body between the first and second strands and pulled down that bottom wire and was immediately electrocuted.

Anderson Cooper: How did you get past him?

Shin Dong-hyuk: I just crawled over his back.

Anderson Cooper: So you climbed-- you literally climbed over him?

Shin Dong-hyuk: Yeah. Yes.

He was a fugitive now in rural North Korea -- on the run in one of the poorest, most repressive countries in the world. But that's not how it seemed to him.

Anderson Cooper: What did the outside world look like?

Shin Dong-hyuk: It was like heaven. People were laughing and talking as they wanted. They were wearing what they wanted. It was very shocking.

Anderson Cooper: How did you manage to get out of North Korea?

Shin Dong-hyuk: I was just trying to get away from camp and I ended up going north. And on the northern side people talked a lot about China.

Anderson Cooper: Did you know where China was?

Shin Dong-hyuk: No. Not at all. It just happened that the way I was going was towards the border.

With amazing luck and cunning, Shin managed to steal and bribe his way across the border, and quietly work his way through China, where he would have been sent back if he was caught. In Shanghai, he snuck into the South Korean consulate and was granted asylum.

In 2006 he arrived in South Korea with not a friend in the world. He was so overwhelmed by culture shock and post-traumatic stress he had to be hospitalized.

More than seven years later, it's remarkable how far Shin's come. He's 30 now, has made friends and built a new life for himself in Seoul, South Korea. But old demons from Camp 14 are never far behind and Shin now admits there was something he was hiding. Two years ago, he finally confessed to author Blaine Harden.

Blaine Harden: When he first told me about the execution of his mother and brother, he didn't say that he had turned them in.

Anderson Cooper: You reported your mother and your brother?

Shin Dong-hyuk: Yes.

Anderson Cooper: What did you hope to get out of reporting your mother and your brother?

Shin Dong-hyuk: Being full for the first time.

Anderson Cooper: More food?

Shin Dong-hyuk: Yes. But the biggest reason was I was supposed to report it.

Anderson Cooper: Why was Shin tortured after ratting out his mother and brother?

Blaine Harden: The guard who he ratted out to did not tell his superiors that he got the information from Shin.

Anderson Cooper: So the guard basically was trying to claim credit?

Blaine Harden: Yes.

It was only after seeing what family life was like outside Camp 14 that Shin says he started to feel guilt about what he had done to his own mother and brother.

Shin Dong-hyuk: My mother and brother, if I could meet them through a time machine I would like to go back and apologize. By telling this story I think that I can compensate, kind of repent for what I did.

Repentance has taken Shin all over the world. He speaks at human rights rallies, meets with U.S. congressmen and is telling his story to us in part because he's frustrated by how much attention the press pays to North Korea's new leader Kim Jong Un and his wife and how little attention gets paid to the people in the camps. In South Korea, he and some friends started an Internet talk show designed to tell the world what's really going on in the North.

As for that taste of freedom he risked his life for he can eat all the broiled chicken he wants now. But admits it hasn't given him the satisfaction he'd hoped for.

Shin Dong-hyuk: When I eat something good, when I laugh with my friends or, you know, when I make some money, I'm excited. But that's only momentary. And right afterwards I start worrying again.

Anderson Cooper: You worry about what now?

Shin Dong-hyuk: What I worry about now is all of those people in the prison camps. Children are still being born there and somebody is probably being executed.

Anderson Cooper, anchor of CNN's "Anderson Cooper 360," has contributed to 60 Minutes since 2006. His exceptional reporting on big news events has earned Cooper a reputation as one of television's pre-eminent newsmen.